Simultaneous improvements of strength and toughness in topologically interlocked ceramics

Abstract

Topologically interlocked materials (TIMs) are an emerging class of architectured materials based on stiff building blocks of well-controlled geometries which can slide, rotate, or interlock collectively providing a wealth of tunable mechanisms, precise structural properties, and functionalities. TIMs are typically 10 times more impact resistant than their monolithic form, but this improvement usually comes at the expense of strength. Here we used 3D printing and replica casting to explore 15 designs of architectured ceramic panels based on platonic shapes and their truncated versions. We tested the panels in quasi-static and impact conditions with stereoimaging, image correlation, and 3D reconstruction to monitor the displacements and rotations of individual blocks. We report a design based on octahedral blocks which is not only tougher (50×) but also stronger (1.2×) than monolithic plates of the same material. This result suggests that there is no upper bound for strength and toughness in TIMs, unveiling their tremendous potential as structural and multifunctional materials. Based on our experiments, we propose a nondimensional "interlocking parameter" which could guide the exploration of future architectured systems.

Dielectric tetrahedrons as terahertz resonators switched from perfect absorber to reflector

“…Fabrication procedure of ZrO 2 ceramic tetrahedrons. The ZrO 2 tetrahedrons used in the experiments are fabricated with a replica casting technique 18 from a mold of negative replica of silica tetrahedron templates, as shown in Fig. 4a.…”

“…Tetrahedrons have the simplest 3D geometry 17 . They are not only basic components of natural materials, but also building blocks to form complex structures 17,18 . On one hand, a regular tetrahedron is highly symmetric, where all faces are of the same shape and size.…”

“…However, the EM properties of dielectric tetrahedrons in terahertz frequency range have been little explored, because the requirements of high permittivity materials and the consequent difficulties in fabrication of micro-size dielectric tetrahedrons bring great challenges. Although there are a few studies on the synthesize and the assembly of nano metallic triangular pyramids 14 and the tetrahedral dices in millimeter scale 18 , the fabrication of regular tetrahedrons in the scale of subwavelength of terahertz frequency range has not been realized, so the terahertz properties of tetrahedrons are still unclear.…”

Short review on architectured materials with topological interlocking mechanisms

“…It shows that stiffness increases with increasing interlocking angle. Furthermore, it has been demonstrated analytically, numerically, and experimentally that with convex polyhedral building blocks, both stiffness and toughness can be increased simultaneously.…”

Mechanics of Chiral Honeycomb Architectures With Phase Transformations

“…Architectured materials offer the potential to address these and other limitations in functionality by effectively "bridging" material behavior across a broad range of disparate length scales [5]. The unusual properties of architectured materials (e.g., negative Poisson's ratio [6], simultaneous high strength, and toughness [7]) are achieved by combining or "blending" geometrical designs at different length scales together with individual material combinations, forming a single architecture or hybrid material with properties that differ from those of the constituent materials [8][9][10]. This can be accomplished with a unit cell design that allows the material to either exploit periodicity or randomness.…”